Self-priming centrifugal pump



E. 11, 3949.. H. LAUCHENAUER 2,458,607

SELF-PRIMING CENTRIFUGAL PUMP Filed April 21, 1945 2 Sheets-Sheet l /NVENT OR.- HERMA NN PLAUCHENAUER Jan H, 1949. H. LAUCHENAUER SELF-PRIMINGCENTRIFUGAL PUMP Filed April 21, 1945' 2 Sheets-Sheet 2 R? R L m A R N NE NEfl v VAHK NMG A /RU 14B EAHVI Patented Jan. 11, 1949 UNITED STATESPATENT OFFICE Application April 21, 1945, Serial No. 589,492 InSwitzerland June 13, 1944 was inserted directly in the pressure pipe,and

the ejector directly connected to the latter, making it necessary tohave the pressure line extended below the level of the pump, in order topermanently remain filled with water. However, with this arrangement,the ejector was permanently kept running during the operation of "thepump, thus continuously causing eddies to rise in the water circulationinside the pump which was accompanied by a corresponding loss of energy,because an essential part of the.total delivery was traversing saidejector. To overcome this drawback it' was proposed to insert in thepressure pipe below the separator, a second ejector,

connected with the ejector of the suction pipe,

and acting in the delivery direction. This seca 0nd ejector which wastraversed by the total delivery, would certainly have compensated thecirculation during normal running but resulted again in a loss ofenergy, owing to its throttling action. Furthermore, there was atendency toobstruction of the nozzle of the second ejector whiledelivering liquids carrying large solid bodies,

such as in pumps forstone dredgers. Pumpsof the last mentioned kind hadthe further drawback, that the stones carried along with the water whichaccording to the delivery of the pump, often reached aweight of severalkilograms, were then violently thrown against the walls of the' airseparator vessel, resulting in latter.

According to the invention, this drawback is overcome in that the airseparator, instead of being inserted directly in the pressure pipe, isarranged in shunt, and the ejector nozzle condamage of the nected to abranch pipe of said pressure pipe.

With this arrangement, only the quantity of liquid which is absolutelyrequired for the selfpriming when starting the pump, is flowing throughthe suction ejector, therefore during normal operation, the circulationwithin the pump system, will accordingly be equally reduced, and

' in virtue of the inertia of the delivery flow in the pressure piping,no solid bodies can penetrate 8 Claims. (Cl. 10311 3) the additionalejector and the two latter, a 1ongitudinal and a transversal sectionview of the into the air separator vessel. By the provision of a grateinthe connection between the air separator and the pressure pipeprovided with a stripper device to be externally operated, the securityof preventing solid bodies fromentering the air separator vessel, canstill further be increased.

An additional suction ejector communicating with the pressure side ofthe pump should preferably be inserted in the ejector pipe; thisadditional ejector providing a suction effect on the pressure side ofthe pump, thereby causing a load reduction of the thrust bearing of thepump.

On the accompanying drawings, the constructional form of the pump,according to the invention, is illustrated, whereby:

Fig. 1 is a schematical longitudinal elevation view of a centrifugalpump group, of which Fig. 2 shows an elevation infront view, an

Fig. 3 a top plan view;

Fig. 4, 5 and 6 are drawn to a larger scale and show: the first, alongitudinal section --view of connection between the air separatorvessel and the pressure pipe;

Fig. '7 and 8 show on a still larger scale, a vertical section view oftwo diiferent embodiments of the connection between the air separatorvesseland the pressure pipe.

The pump plant shown in the drawings, intended to be used as a stonedredger pump, comprises the centrifugal pump P directly coupled to theelectric motor M. The suction pipe 8, ex-

tending above the pump, is provided on its apex with an air inlet valveV. The liquid flow entering through the suction-pipe S, mingled withstones and mud, is expelled through the pressure pipe D. The airseparator vessel L, is arranged in shunt to the pressure pipe D at sucha height, I

dotted line, in such a manner, that after a stoppage, the self-primingbecomes efl'ective by means of the ejector. The ejector to the nozzle 2of which water is delivered through a branch pipe I connected with thebottom of the air separator vessel L, which nozzle protrudes into theconnecting bend 3 of the suction pipe, when put into operation producesthe extraction of air from the suction pipe S, and the suction begins,so

that only a small quantity of water flows through the pump. In front ofthe nozzle 2, a second and smaller nozzle 4, is inserted in the pipe I,a pipe 5 connecting said second nozzle with the pressure side of thepump at 5. This latter nozzle 4, constitutes an additional suctionejector, owing to the fact, that it produces a decrease of separation ofair.

w effect is produced in the direction of the arrow,

pressure on the pressure or back side of the pump rotor, resulting in areduction of the load of the ball thrust bearing K of the pump.

The air separator vessel L, is connected to the section II of thepressure pipe, by means of a connecting chamber 10, the junctionaperture of which is closed in the pipe I I, by longitudinally arrangedgrate bars l2. In the transversal direction of the chamber i0, isjournalled a shaft l3, to which are secured stripper rods I4 locatedbetween the grate bars and extending over their whole length, therebypermitting the cleaning of the grate from little stones which havebecome jammed between the grate bars. On the exterior end of shaft I 3,laterally protruding through a stuffing-box, is secured an operatinglever l5, permitting an oscillatory motion of said shaft together withthe stripper rods, thereby giving the possibility of always keeping thepassages through the grate to the air separator vessel unobstructed.

Owing to this arrangement, all damage to the air separator vessel bystones carried in the flow of water, is completely excluded.

On the suction and pressure side of the pump, are connected clearingpipes 'l and 8, to keep the pump clean of sand and gravel, by means ofwater delivered under high pressure through the pressure line 9.

Under certain circumstances, it is also desirable to provide means for areduction of the interior circulation produced in the pump system by theinfluence of the ejector and to reduce the energy loss.

Two different arrangements to realize this requirement are shown inFigs. 7 and 8.

Where the embodiment according to Fig. 7 is concerned, a connection isformed in a similar manner as above described, between the air separatorvessel L, and a lateral connecting chamber which join laterally in apipe 2|, concentrically surrounding the pressure pipe I I, and thediameters of the two concentric pipes which are placed in such a mannerto allow for a small annular space remaining between these pipes whichare connected to each other at their ends by flanges. The interior pipeI l is provided on the part of its circumference located near thechamber In by upwardly inclined ports 22 for the At the same time, asuction drawn as a dotted line under the influence of the water flowingin the pressure pipe in the direction of the under arrow, said suctioneffect being opposed to the suction effect of the pump 2, 4, i. e. tothe inner circulation and annuls same to an essential part. With thisarrangement the solid bodies are also safely prevented from entering theair separator vessel.

The embodiment shown in Fig. 8 is particularly effective. The pressurepipe II is joining concentrically an outer pipe 3|, connected laterallywith the chamber l0, and having a greater diameter than the pressurepipe H, and the top end of the latter is connected with its outwardlycurved margin with the outer pipe 3| which latter is extended with thesame diameter so as to form the pressure pipe II. In the outwardlycurved margin are provided around the circumference bores 32 abovewhich, owning to this arrangement, is created by the traversing pressurewater, a Venturi effect in the enlarged part of the pres sure pipe,resulting in a suction effect in the direction of the dotted arrow. Whenthe pump is functioning normally, the inner circulation is consequentlyannuled to an essential part.

I do not limit my invention to the structure shown and described asmodifications, within the scope of the appended claims, may be madewithout departing from the spirit of my invention.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent is:

1. A self-priming pump system comprising a centrifugal pump, a suctionconduit extending above said pump, an ejector inserted in and having anozzle terminating and discharging into said suction conduit, adischarge conduit, an air separator disposed separated from saiddischarge conduit and connected for fluid flow therewith, and a conduitconnecting said air separator and said ejector and conducting fluid fromsaid separator into said nozzle.

2. A self-priming pump system comprising a centrifugal pump, a suctionconduit extending above said pump, an ejector inserted in and having anozzle terminating in and discharging into said suction conduit, adischarge conduit, an air separator disposed separately from saiddischarge conduit, a conduit interconnecting said discharge conduit andsaid separator, a grate means disposed in said last mentioned conduitand comprising movable grate closing and opening means, and operatingmeans connected with said closing and opening means and extendingoutside of said last mentioned conduit.

3. A pump system as defined in claim 1, having debris retaining meansconnected with said discharge conduit and comprising ports extending forfluid flow substantially in the direction of imaginary flow linesextending from said air separator into the direction of the normal flowof the fluid through said discharge conduit.

4. A self-primin pump system comprising a centrifugal pump, a suctionconduit extending above said pump, an ejector inserted in and having anozzle terminating in and discharging into said suction conduit, adischarge conduit, an air separator disposed separately from saiddischarge conduit, a conduit interconnecting said discharge conduit andsaid separator, said last mentioned conduit comprising a portion partlysurrounding and spaced from said discharge conduit, and said dischargeconduit comprising port means extending substantially in the directionof imaginary flow lines extending from said separator into the directionof the normal flow through said discharge conduit.

5. A self-priming pump system comprising a centrifugal pump, a suctionconduit extending above said pump, an ejector inserted in and having anozzle terminating in and dischargin into said suction conduit, adischarge conduit, an air separator disposed separately from saiddischarge conduit, conduit means interconnecting said discharge conduitand said separator, said discharge conduit extending into said conduitmeans and terminating therein and having an end portion slightly spacedfrom the inside of said conduit means, and said conduit means continuingas discharge conduit beyond said end portion.

6. A self-priming pump system comprising a centrifugal pump, a suctionconduit extending above said pump, an ejector inserted in and having anozzle terminating in and discharging into said suction conduit, adischarge conduit, an air separator disposed separately from saiddischarge conduit, conduit means interconnecting said discharge conduitand said separator, said discharge 5 conduit extending into and beingpartly surrounded by and spaced from said conduit means and having aflared end portion extending to the inside of said conduit means, saidconduit means continuing as discharge conduit beyond said end portion,and said end portion having openings interconnecting said dischargeconduit and said conduit means for fluid flow.

7. A pump system as defined in claim 1, having an additional ejectorhaving a nozzle discharging into the conduit interconnecting said airseparator and said first ejector, and a conduit connecting saidadditional ejector and the pressure or back side of the pump.

8. A pump system as defined in claim 1, having cleaning conduitssupplied with a high pressure fluid connected with the front and withthe back side of the pump,

HERMANN LAUCHENAUER.

REFERENCES CITED The following references are of record in the file ofthis patent:

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